Ammunition with Device for Holding the Pyrotechnic Charge of the Ammunition

ABSTRACT

Ammunition comprises, along a longitudinal axis, a fuse in the form of a tip, an ammunition body and a skirt, the ammunition body of cylindrical form with axis of revolution merged with the longitudinal axis, having, between a front end and a rear end, a circular cylindrical wall delimiting a loading compartment containing a pyrotechnic charge, the ammunition body being sealed at its front end by the fuse and at its rear end by the skirt attached to the ammunition body. The ammunition body includes, in the loading compartment, between its two ends, a central core having n fins each comprising at least one edge, in the axis of revolution, attached to the skirt, n being greater than or equal to 1, to separate the pyrotechnic charge into at least two portions on either side of a given fin Ei. Applications are to cannon or mortar type ammunition.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to foreign French patent application No. FR 1101633, filed on May 27, 2011, the disclosure of which is incorporated by reference in its entirety.

FIELD OF THE INVENTION

The invention relates to ammunition which is subject, on firing, to significant axial and roll accelerations.

BACKGROUND

A large number of artillery systems, such as cannons and mortars, use ammunition comprising a belt. The cannon is provided with internal rifling marks intended to impart a rotational movement on the ammunition and thus enhance its stability in trajectory.

The rifled ammunition is not only subject to an axial thrust like smooth ammunition, upon the activation of its propulsive charge, but is also placed in rotation by virtue of the helical rifling marks located on the internal wall of the cannon barrels which drive the ammunition via its belt according to a defined helical angle. These belts are generally of “rifled” type for mortar projectiles or of “forcing” type for cannon shells.

Such ammunition is dimensioned such that it is capable of withstanding the stresses due to the firing environment generated by a propulsive charge. This propulsive charge is, depending on the ammunition, loaded into a cartridge case or positioned on a charge-holding tail groove.

The ammunition usually contains a load, for example a pyrotechnic load (fumigant, explosive, lighting, etc.), held in the body of the ammunition by internal walls of the ammunition. This load is, by its chemical composition and depending on the ambient temperature, of non-solid type, whether pasty, liquid, or viscous.

Upon firing, in a so-called “cannon shot” phase, the ammunition is subjected simultaneously to an axial thrust by the propulsive charge and to a rotation by the rifling marks of the cannon subjecting the body of such ammunition to significant axial and roll accelerations. The internal pyrotechnic load of the ammunition is generally placed in rotation by the adhesion forces being exerted at the “load/ammunition body” interface during the firing phase.

The internal load, by its nature, is not sufficiently rigid to withstand the deformations upon firing and tends to be packed into the rear portion of its container (body of the ammunition) under the effect of the longitudinal acceleration and to be twisted (torsion) on itself under the effect of the angular acceleration.

These deformations, which are more or less significant depending on the viscosity or the hardness of the load, cause the adhesion of the load with its container (ammunition body) to be degraded, result in stresses greater than the strength of the load material, and thus create cracks in this material, thus degrading the desired terminal effect and generating possible safety problems from the “cannon shot phase” to the end of the firing safety distance.

For loads in the liquid state, the problem is different in that they are not in cohesion with their container (ammunition body) because of their state. In this state, and depending on the viscosity, this type of load is subject to a more or less rapid rotational movement, thus generating a more or less significant angular speed difference between the load and its container (ammunition body).

The firing phase is followed by a so-called “ballistic flight phase” of the ammunition, and a load in the pasty state which is no longer under the effect of the angular and axial acceleration tends to resume its initial form by restoring the potential energy stored in its packing and in its torsion. These internal movements of the load are not in harmony with the kinetics of all the other components of the ammunition and tend to result in disturbances to the stability of the ammunition in ballistic flight.

These disturbances are all the more significant for a load of liquid type which, not being in cohesion with the container, that is to say with the body of the ammunition, and having an angular speed difference relative to its container, tends to be harmonized during the “flight phase” with the latter, which causes the speed of rotation of the load to increase to the detriment of the speed of rotation of the ammunition which drops as a function of the masses involved, of the coefficient of friction between the load and the body of the ammunition (adhesion) and of the geometry of the container.

The internal movements due to the deformations of the load and the reduction of the gyroscopic effect due to the reduction of the angular speed of the ammunition may cause the ammunition to be less stable during the “flight phase”, to be more sensitive to the external stresses encountered in its trajectory and ultimately to miss the target.

SUMMARY OF THE INVENTION

To overcome the drawbacks of the ammunition of the prior art, the invention proposes ammunition comprising, along a longitudinal axis XX′, a fuse in the form of a tip, an ammunition body and a skirt, the ammunition body, of cylindrical form with axis of revolution AA′ merged with the longitudinal axis XX′, having, between a front end and a rear end, a circular cylindrical wall delimiting a loading compartment containing a pyrotechnic charge, the ammunition body being sealed at its front end by the fuse and at its rear end by the skirt attached to the ammunition body, characterized in that the ammunition body includes, in the loading compartment between its two ends, a central core having n fins E1, E2, . . . Ei, . . . En each comprising at least one edge, in the axis of revolution AA′, attached to the skirt, i being the rank of the fin, n being greater than or equal to 1, to separate the pyrotechnic charge into at least two portions on either side of the fin Ei.

In one embodiment, the ammunition comprises, between the fuse and the ammunition body, a booster for igniting the pyrotechnic charge, the booster of circular cylindrical form having an external booster portion linking the ammunition body and the fuse and a booster body inside the ammunition body.

In another embodiment, the circular cylindrical wall of the ammunition body comprises an outer surface of external diameter Dpe and an inner surface of internal diameter Dpi forming the loading compartment containing the central core and the pyrotechnic charge.

In another embodiment, the skirt of cylindrical form of axis of revolution CC′ ends, on the side of the ammunition body, with a skirt wall of circular form in a plane P2 perpendicular to the axis of the skirt, the skirt having as many grooves R1, R2, . . . Ri, . . . Rn as the central core has fins, the grooves opening onto the skirt wall and ending in the skirt with a bottom in a plane P3 perpendicular to the longitudinal axis XX′ of the ammunition, the n fins E1, E2, . . . Ei, . . . En of the central core comprising, on the side of the rear end of the ammunition body, rear fin ends ending, in a plane P6 perpendicular to the axis AA′ of the central core, with fin edges, a rear fin end of the fin Ei of rank i being inserted into the respective groove Ri of the same rank i of the skirt, the fin edges being in contact with the bottoms of the grooves so as to render the central core attached in rotation and in translation to the skirt and, consequently, to the ammunition body, the link of the fins with the skirt being of tenon/mortise type, the tenons being the rear portions of the fins and the mortises being the grooves R1, R2, . . . Ri, Rn in the skirt.

In another embodiment, a rigid link of the fins with the skirt is produced, either by gluing the rear fin ends in the n grooves R1, R2, . . . Ri, . . . Rn in the case of a link of “tenon/mortise” type, or by screwing, or by welding on the edge of the fins, the latter solution being able to be exempted from a link of tenon/mortise type.

In another embodiment, the n fins E1, E2, . . . Ei, . . . En comprise, on the side of the front end of the ammunition body, front fin portions inscribed in a cylindrical surface of diameter equal to the diameter D1 of a circular cylindrical surface portion of the inner surface of said front end of the ammunition body to produce a link of the central core with said ammunition body, of centering link type.

In another embodiment, a skirt-central core assembly being produced in a single piece, the skirt of axis of revolution CC′ comprises, on the side of the ammunition body, the central core having n fins E1, E2, . . . Ei, . . . En attached to the skirt, at least by their edges in the axis of revolution CC′, the skirt with the central core being screwed onto the rear end of the ammunition body to seal said ammunition body, the front portions of the fins being free of contact with the wall of the ammunition body to produce a mounting of the central core in the ammunition body of “overhang” type.

In another embodiment, an ammunition body-skirt-central core assembly being produced in a single piece, the ammunition body comprises a cylindrical wall of axis of revolution AA′ merged with the longitudinal axis XX′ of the ammunition, on the side of the front end of the ammunition body, the circular opening for the booster and, on the side of the rear end of the ammunition body, a rear body portion forming a skirt, the ammunition body comprising, in the axis AA′, the n fins E1, E2, . . . Ei, . . . En attached together, on the one hand, by their edges in the axis of revolution AA′ of the ammunition body and, on the other hand, by other edges of the fins, of the wall of said ammunition body and of the skirt, the fins forming, with the skirt and the circular wall, cells for the pyrotechnic charge.

In another embodiment, an ammunition body-central core assembly being produced in a single piece, the ammunition body comprises a cylindrical wall of axis of revolution AA′ merged with the axis XX′ of the ammunition and a central core attached to said cylindrical wall, the cylindrical wall comprising, on the side of the front end of the ammunition body, the circular opening for the booster and, on the side of the rear end of the ammunition body, a rear opening sealed by a skirt, the fins E1, E2, . . . Ei, . . . En of the central core being attached, on one side, by their edges in the axis AA′ of the ammunition body and by other edges, parallel to the axis AA′ of the ammunition body, of the cylindrical wall of the ammunition body, the fins forming, with the skirt and the cylindrical wall, cells for the pyrotechnic charge.

In another embodiment, the loading compartment comprises a common loading area followed by a compartmented area, the common loading area being delimited by the booster, the ammunition body wall and by the plane formed by the front end portions of fins of the central core, the compartmented area being delimited by the ammunition body wall and the skirt, the fins E1, E2, . . . Ei, . . . En forming, with the ammunition body wall, cells for the pyrotechnic charge of the ammunition.

In another embodiment, the n fins forming the central core are preferentially distributed regularly around the axis of revolution AA′ of the ammunition body to form identical cells intended to contain the pyrotechnic charge.

In another embodiment, the central core comprises, in the coupling axis of the edges of the fins, a passage over at least a portion of the length of the central core for the introduction of a pyrotechnic tube igniter.

In another embodiment, the wall of the passage, formed by the edges of the n fins E1, E2, . . . Ei, . . . En comprises orifices perpendicular to the axis of the passage enabling the pyrotechnic tube igniter, through these orifices, to laterally ignite, along said axis CC′, the pyrotechnic charge of the ammunition.

A main objective of the ammunition according to the invention is to keep the detonator of the ammunition during the “cannon shot phase” in intimate contact with the pyrotechnic load and to accelerate in rotation, through the fins of the central core, all of the pyrotechnic load with the same acceleration in rotation as the container, that is to say the body of the ammunition.

Another objective is to enhance the stability of the ammunition during the “flight phase” by avoiding the internal movements or the deformation of the pyrotechnic charge.

Another objective is to render the ammunition less sensitive to the external stresses encountered in its trajectory to reach the target.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood from descriptions of ammunition embodiments according to the invention with reference to the indexed drawings in which:

FIG. 1 a represents an axial view of ammunition according to the invention;

FIG. 1 b represents an axial cross-sectional view of the ammunition of FIG. 1 a;

FIG. 1 c shows a detail in cross section of the front end of the ammunition of FIG. 1 b;

FIG. 1 d shows a detail in cross section of the rear end of the ammunition of FIG. 1 b;

FIG. 2 shows a central core of the ammunition of FIG. 1 a;

FIG. 3 shows a cross section of the ammunition of FIG. 1 a in a plane perpendicular to the ammunition;

FIG. 4 shows a perspective exploded view of the ammunition of FIG. 1 a;

FIG. 5 a shows a axial cross-sectional view of a first variant of the ammunition of FIG. 1 a;

FIG. 5 b represents a perspective view of the first variant of the ammunition of FIG. 1 a;

FIG. 5 c shows a detail in cross section of the front of the ammunition of FIG. 5 a;

FIG. 6 a shows an axial cross-sectional view of a second variant of the ammunition according to the invention;

FIG. 6 b shows a cross-sectional view in a plane perpendicular to the axis of the ammunition of FIG. 6 a;

FIG. 7 a shows an axial cross-sectional view of a third variant of the ammunition according to the invention;

FIG. 7 b shows a cross-sectional view in a plane perpendicular to the axis of the ammunition of FIG. 7 a;

FIG. 8 a shows an axial cross-sectional view of a fourth variant of the ammunition according to the invention;

FIG. 8 b shows a cross-sectional view in a plane perpendicular to the axis of the ammunition of FIG. 8 a;

FIG. 9 a shows a perspective view of a variant of the central core of the ammunition according to the invention and;

FIG. 9 b shows a cross-sectional view in a plane perpendicular to the axis of the central core of FIG. 9 a.

DETAILED DESCRIPTION

FIG. 1 a represents an axial view of ammunition according to the invention. FIG. 1 b represents an axial cross-sectional view of the ammunition of FIG. 1 a.

The ammunition of FIGS. 1 a and 1 b of cylindrical form of axis of revolution XX′ essentially comprises an ammunition body 10, of circular cylindrical form of axis of revolution AA′, having two ends, a front end and a rear end, on the side of the front end, a fuse 20 and a booster 22 coupled to the ammunition body 10, on the side of the rear end, a skirt 24.

The fuse 20 in the form of a tip, intended to be directed toward a target (not represented in the figures) is coupled to the booster 22, if necessary, via a tapered adapting ring 26. The booster 22 of circular cylindrical form comprises an external booster portion 28 and a booster body 30 inside the ammunition body. The external booster portion, also tapered, couples, without discontinuity, the ammunition body 10 with the fuse 20 or the adapting ring 26.

The skirt 24 is also tapered with a shallow slope of axis AA′, the smallest diameter of which forms the rear end of the ammunition.

The ammunition body 10 comprises a circular cylindrical ammunition body wall 31 having an outer surface 32 of external diameter Dpe and an inner surface 33 of internal diameter Dpi forming a loading compartment 36 containing, according to a main feature of the invention, a profiled central core 38 and a pyrotechnic charge 39.

The diameter Dpi of the inner surface 33 of the ammunition body wall 31 reduces progressively in diameter toward the front end of the ammunition body to form a circular opening 40 for the passage of the booster body 30 inside the ammunition body 10. This opening 40 is used to load the ammunition with a pyrotechnic charge of liquid or pasty type.

FIG. 1 c shows a cross-sectional detail of the front end of the ammunition of FIG. 1 b. FIG. 1 d shows a cross-sectional detail of the rear end of the ammunition of FIG. 1 b.

The inner surface 33 of the wall 31 of the ammunition body 10 comprises, on the side of the booster 22, a circular cylindrical surface portion 46 of diameter D1 and a discontinuity (see FIG. 1 c) forming a body shoulder 50 in a plane P1 perpendicular to the axis AA′ to block the central core 38 in the ammunition body, and on the side of the skirt 24 (see FIG. 1 d), a wall threading 54 of diameter Dpa for screw-fastening the skirt 24 onto the ammunition body 10.

The skirt 24 sealing the rear end of the ammunition body 10 comprises, on the side of the ammunition body, a circular outer surface 58 of diameter Dpa comprising a skirt threading 60 intended to be screwed onto the wall threading 54 to securely attach the skirt 24 to the ammunition body 10. The outer surface 58 of the skirt 24 is prolonged by another outer surface 62 aligned on the outer surface 32 of the ammunition body forming another skirt shoulder 64 to block the skirt on the ammunition body in its screw-fastening.

The skirt 24 ends, on the side of the ammunition body 10, with a skirt wall 68 of circular form in a plane P2 perpendicular to the axis of the skirt. The skirt 24 comprises four grooves R1, R2, R3, R4 opening onto the skirt wall 68, each groove ending in the skirt with a bottom 70 in a plane P3 perpendicular to the axis AA′ of the skirt. The four grooves, regularly distributed around the axis of the skirt merged with the axis XX′ of the ammunition, are intended to rotationally and translationally block the profiled central core 38 in the ammunition body 10.

FIG. 2 shows a central core of the ammunition of FIG. 1 a.

The profiled central core 38 comprises four fins E1, E2, E3, E4 attached together by one of their edges b1 in an axis of revolution AA′ merged with the longitudinal axis XX′ of the ammunition. The fins are in planes P4, P5 perpendicular to one another passing through the axis of revolution AA′ and inscribed over a large portion of the rear side of the ammunition in a circular cylindrical surface of diameter D2.

The fins E1, E2, E3, E4 comprise, on the side of the front of the ammunition, front fin portions 84 inscribed in a cylindrical surface of diameter equal to the diameter D1 being progressively coupled to the diameter D2 of the fins. The diameter D1 of the front fin portions 84 is that of the circular cylindrical surface portion 46 of the inner surface 33 of the ammunition body 10 to produce a link with said body of centering link type. In this embodiment, the diameter D1 of the ammunition body 10 corresponds to a complete circular cylindrical surface whereas the diameter D1 of the profiled central core 38 is defined by four lines corresponding to the edges of the four fins inscribed in this diameter D1.

The front fin portions 84 are coupled to front fin ends 86 inscribed in a cylindrical surface of diameter D3 less than the diameter D1 of the front fin portions 80 to form a front fin shoulder 88 intended to abut with the body shoulder 50 of the ammunition wall 30.

The fins E1, E2, E3, E4 comprise, on the rear side of the ammunition, rear fin ends 100 inscribed in a cylindrical surface of diameter D4 less than the diameter D2 of the fins ending, in a plane P6 perpendicular to the axis AA′ of the central core 38, with fin edges 102. The rear fin ends 100 are intended to be inserted into the respective grooves R1, R2, R3, R4 of the ammunition skirt 24, the fin edges 102 being in contact with the bottoms 70 of the grooves so as to securely attach the profiled central core 38 in rotation and in translation to the skirt and consequently to the ammunition body 10.

The link of the fins with the skirt 24 is of tenon/mortise type, the tenons being represented by the rear portions of the fins 100 and the mortises by the grooves R1, R2, R3, R4 in the skirt 24.

FIG. 3 shows a cross section of the ammunition of FIG. 1 a in a plane perpendicular to the ammunition.

FIG. 4 shows a perspective exploded view of the ammunition of FIG. 1 a.

The profiled central core 38 is inserted into the ammunition body 10 by its rear end and the skirt 24 is screwed into the ammunition body wall 31.

The profiled central core 38 is thus held radially centered in the axis XX′ of the ammunition by its two ends, the skirt 24 being fastened to the ammunition body 10 by virtue of the skirt and wall threadings 60 and 54.

The geometry of the assembly is such that the length L2 defined by the distance between the four front fin shoulders 88 of the profiled central core 38 and the fin edges 102 is fitted to the length L1 defined by the distance between the shoulder 50 of the ammunition body 10 and the bottoms 70 of the four grooves R1, R2, R3, R4 of the skirt.

The profiled central core 38, thus held axially and radially in the ammunition, makes it possible to rigidly compartment the assembly of the ammunition body 10 and skirt 24 when assembled.

In a state of assembly of the ammunition comprising the profiled central core 38 locked in the ammunition body 10 by the skirt 24 screwed into the wall of the ammunition body, the volume encompassed by the ammunition body comprises, on the side of the front end of the ammunition body, a common loading area 120 forming a non-compartmented volume and, in the ammunition body, an area 124 compartmented by the fins E1, E2, E3, E4 of the profiled central core 38.

The common loading area 120 is delimited by the booster 22, the ammunition body wall 31 and by the plane formed by front fin end portions 86.

The compartmented area is limited by the ammunition body wall 31 and the skirt wall 68, the fins E1, E2, E3, E4 forming, with the ammunition body wall 31, four cells 106 for the pyrotechnic load 39 of the ammunition.

Most of the pyrotechnic load is thus produced in four compartmented lobes 108 in the four cells 106, only the common loading area 120 being of a single piece to ensure an optimal pyrotechnic interface with the booster 22 in order to uniformly distribute the ignition of the pyrotechnic load 39, if the latter is of explosive type, in the four lobes 108.

If the pyrotechnic load 39 is of liquid or pasty type, the skirt 22 being screwed onto the ammunition body, this load is introduced into the space reserved for loading via the circular orifice 40 at the front of the ammunition body 10 before the mounting of the fuse, the adapting ring 26 and the booster 22.

If the pyrotechnic load is rigid, it will be positioned on the profiled central core 38, then before the skirt 22 is screwed onto the ammunition body, the central core with its rigid pyrotechnic load will be introduced into the ammunition body 10 through the rear end of the ammunition body.

When the ammunition is used, during the “cannon shot phase”, the skirt 24, by virtue of the “tenon/mortise” link, rotationally drives the profiled central core 38 which itself is dimensioned to withstand the angular acceleration of the ammunition. The central core 38 in turn rotationally drives the four pyrotechnic load lobes 108 via its four cells 106 in harmony with the ammunition as a whole, thus preventing any torsion effect on the pyrotechnic load or effect of angular speed difference between the pyrotechnic load and the ammunition body 10.

The use in the ammunition body 10 of the profiled central core 38 makes it possible, by virtue of its fins, to significantly increase the attachment (or adhesion) surface area of the pyrotechnic load with the mechanical structure of the ammunition, that is to say, the ammunition body 10 with the profiled central core 38 attached to the ammunition body, and thus preserve the adhesion of the pyrotechnic load with its container consisting of the ammunition body 10 with the profiled central core 38. This profiled central core structure also makes it possible to significantly lessen the packing of the pyrotechnic load in the rear portion of its container and to not generate cracks in the material forming the pyrotechnic load.

The profiled central core 38 also makes it possible to dispense with bonds between the pyrotechnic load and the ammunition body 10, which are always difficult to implement, and generally employed with explosive loads which are of rigid, or even rubbery (non-liquid), type.

FIG. 5 a shows an axial cross-sectional view of a first variant of the ammunition of FIG. 1 a.

FIG. 5 b represents a perspective view of the first variant of the ammunition of FIG. 1 a.

In this first variant, a profiled central core 150 in the ammunition body 10 is linked only by its rear end to the skirt 24. As in the embodiment represented in detail in FIG. 1 d, the rear fin ends 100 are intended to be inserted into the respective grooves R1, R2, R3, R4 of the skirt 24 of the ammunition, the fin edges 102 being in contact with the bottoms 70 of the grooves so as to make the profiled central core 150 securely attached in rotation and in translation to the ammunition body 10. The link of the fins E1, E2, E3, E4 with the skirt 24 is of tenon/mortise type, the tenons being represented by the rear ends of the fins 100 and the mortises by the grooves R1, R2, R3, R4 in the skirt 24.

The link of the fins with the skirt 24 can be produced either by gluing the rear fin ends 100 in the grooves R1, R2, R3, R4 in the case of a “tenon/mortise” type link, or by screwing (solution not represented), or by welding on the edge of the fins, the latter solution not requiring a tenon/mortise type link.

FIG. 5 c shows a detail in cross section of the front of the ammunition of FIG. 5 a.

FIG. 5 c notably shows a detail of the front fin ends 154 free of contact with the ammunition body wall 31. In this first variant, the front fin end 154 of the profiled central core 150 has no mechanical link with the ammunition body 10, which makes it possible, among other things, when manufacturing the ammunition, to leave the outer surfaces of the profiled central core 150 and the inner surfaces of the ammunition body 10 in the crude or preform state.

In this first variant, the mounting of the profiled central core 150 in the ammunition body 10 is said to be of “overhang” type.

FIG. 6 a shows an axial cross-sectional view of a second variant of the ammunition according to the invention.

FIG. 6 b shows a cross-sectional view in a plane perpendicular to the axis of the ammunition of FIG. 6 a.

In this second variant, the ammunition comprises a skirt 160-central core 164 assembly produced in a single piece, for example by a “foundry” type manufacturing method.

The skirt 160 of axis of revolution CC′ comprises, on the side of the ammunition body 10, the central core 164 having the fins E1, E2, E3, E4 attached, at least by their edges b1 in the axis of revolution CC′, to the skirt 160. The skirt with the central core 164 is screwed onto the rear end of the ammunition body 10 to seal said ammunition body. The front portions 180 of the fins are free of contact with the circular cylindrical wall 31 of the ammunition body 10, to produce a mounting of the central core 164 in the ammunition body of “overhang” type.

FIG. 7 a shows an axial cross-sectional view of a third variant of the ammunition according to the invention.

FIG. 7 b shows a cross-sectional view in a plane perpendicular to the axis of the ammunition of FIG. 7 a.

In this third variant, the ammunition comprises an ammunition body 200-skirt 208-central core 302 assembly produced in a single piece, for example of foundry type.

The ammunition body 200 comprises a cylindrical wall 202 of axis of revolution AA′ merged with the longitudinal axis XX′ of the ammunition, on the side of the front end of the ammunition body 200, the circular opening 40 for the booster 22 and, on the side of the rear end of the ammunition body, a rear body portion 206 forming a skirt 208. The ammunition body comprises, in the axis AA″, the four fins E1, E2, E3, E4 attached together, on the one hand, by their edges b1 in the axis of revolution AA′ of the ammunition body 200 and, on the other hand, by other edges b2, b3 of the wall 202 of said ammunition body and of the skirt 208. The fins form, with the skirt 208 and the cylindrical wall 202, cells 106 for the pyrotechnic charge 39.

FIG. 8 a shows an axial cross-sectional view of a fourth variant of the ammunition according to the invention.

FIG. 8 b shows a cross-sectional view in a plane perpendicular to the axis of the ammunition of FIG. 8 a.

In this fourth variant, the ammunition comprises an ammunition body 300-central core 320 assembly produced in a single piece, for example of foundry type.

The ammunition of FIG. 8 a comprises an ammunition body 300 having a cylindrical wall 302 of axes of revolution AA′ merged with the axis XX′ of the ammunition and a central core 320 attached to said cylindrical wall 302. The cylindrical wall 302 comprises, on the side of the front end of the ammunition body, the circular opening 40 for the booster 22 and, on the side of the rear end of the ammunition body, a rear opening 304 sealed by a skirt 308. As in the embodiment of FIG. 1 b, the skirt 308 is attached to the ammunition body wall 300 by screw-fastening. To this end, the skirt 308 comprises a threaded portion of diameter Dpa attached to the rear opening, also threaded, of the same diameter Dpa.

In this fourth variant of FIG. 8 a, the fins E1, E2, E3, E4 of the central core are attached, on one side, by their edges b1 in the axis AA′ of the ammunition body and by other edges b2, parallel to the axis AA′ of the ammunition body, to the cylindrical wall 302 of the ammunition body. The fins form, with the skirt 308 and the cylindrical wall 302, the four cells 106 for the pyrotechnic charge.

FIG. 9 a shows a perspective view of a variant of the central core of the ammunition according to the invention.

FIG. 9 b shows a cross-sectional view in a plane perpendicular to the axis of the central core of FIG. 9 a.

In a variant of the central core 38, 150, 164, 220, 320 of the ammunitions of FIGS. 1 a to 8 b, a profiled central core 340 comprises, in the coupling axis CC′ of the edges b1 of the fins, a passage 350 over at least a portion of the length of the central core for the introduction of a pyrotechnic tube igniter. The walls 354 of the passage 350 in the axis CC′ formed by the edges b1 of the fins E1, E2, E3, E4 may also include orifices 360 perpendicular to the axis XX′ making it possible for the pyrotechnic tube igniter, through these orifices, to ignite the pyrotechnic charge of the ammunition laterally along the axis CC′.

The exemplary embodiments described for the ammunition according to the invention are not limited to a central core comprising four fins; the number of fins may be greater or lesser, the fins being distributed regularly around the longitudinal axis of the central core. At the very least, the central core may comprise a single fin to prevent the rotation of the pyrotechnic charge in the ammunition body in the “cannon shot” phase. 

1. Ammunition comprising, along a longitudinal axis XX′, a fuse in the form of a tip, an ammunition body and a skirt, the ammunition body, of cylindrical form with axis of revolution AA′ merged with the longitudinal axis XX′, having, between a front end and a rear end, a circular cylindrical wall delimiting a loading compartment containing a pyrotechnic charge, the ammunition body being sealed at its front end by the fuse and at its rear end by the skirt attached to the ammunition body, the ammunition body including, in the loading compartment between its two ends, a central core having n fins E1, E2, . . . Ei, . . . En each comprising at least one edge, in the axis of revolution AA′, attached to the skirt, i being the rank of the fin, n being greater than or equal to 1, to separate the pyrotechnic charge into at least two portions on either side of the fin Ei.
 2. The ammunition as claimed in claim 1, further comprising, between the fuse and the ammunition body, a booster for igniting the pyrotechnic charge, the booster of circular cylindrical form having an external booster portion linking the ammunition body and the fuse and a booster body inside the ammunition body.
 3. The ammunition as claimed in claim 1, wherein the circular cylindrical wall of the ammunition body comprises an outer surface of external diameter Dpe and an inner surface of internal diameter Dpi forming the loading compartment containing the central core and the pyrotechnic charge.
 4. The ammunition as claimed in claim 1, wherein the skirt of cylindrical form of axis of revolution CC′ ends, on the side of the ammunition body, with a skirt wall of circular form in a plane P2 perpendicular to the axis of the skirt, the skirt having as many grooves R1, R2, . . . Ri, . . . Rn as the central core has fins, the grooves opening onto the skirt wall and ending in the skirt with a bottom in a plane P3 perpendicular to the longitudinal axis XX′ of the ammunition, the n fins E1, E2, . . . Ei, . . . En of the central core comprising, on the side of the rear end of the ammunition body, rear fin ends ending, in a plane P6 perpendicular to the axis AA′ of the central core, with fin edges, a rear fin end of the fin Ei of rank i being inserted into the respective groove Ri of the same rank i of the skirt, the fin edges being in contact with the bottoms of the grooves so as to render the central core attached in rotation and in translation to the skirt and, consequently, to the ammunition body, the link of the fins with the skirt being of tenon/mortise type, the tenons being the rear portions of the fins and the mortises being the grooves R1, R2, . . . Ri, Rn in the skirt.
 5. The ammunition as claimed in claim 4, wherein a rigid link of the fins with the skirt is produced, either by gluing the rear fin ends in the n grooves R1, R2, . . . Ri, . . . Rn in the case of a link of “tenon/mortise” type, or by screwing, or by welding on the edge of the fins, the latter solution being able to be exempted from a link of tenon/mortise type.
 6. The ammunition as claimed in claim 4, wherein the n fins E1, E2, . . . Ei, . . . En comprise, on the side of the front end of the ammunition body, front fin portions inscribed in a cylindrical surface of diameter equal to the diameter D1 of a circular cylindrical surface portion of the inner surface of said front end of the ammunition body to produce a link of the central core with said ammunition body, of centering link type.
 7. The ammunition as claimed in claim 1, wherein, a skirt-central core assembly being produced in a single piece, the skirt of axis of revolution CC′ comprises, on the side of the ammunition body, the central core having n fins E1, E2, . . . Ei, . . . En attached to the skirt, at least by their edges in the axis of revolution CC′, the skirt with the central core being screwed onto the rear end of the ammunition body to seal said ammunition body, the front portions of the fins being free of contact with the wall of the ammunition body to produce a mounting of the central core in the ammunition body of “overhang” type.
 8. The ammunition as claimed in claim 1, wherein, an ammunition body-skirt-central core assembly being produced in a single piece, the ammunition body comprises a cylindrical wall of axis of revolution AA′ merged with the longitudinal axis XX′ of the ammunition, on the side of the front end of the ammunition body, the circular opening for the booster and, on the side of the rear end of the ammunition body, a rear body portion forming a skirt, the ammunition body comprising, in the axis AA′, the n fins E1, E2, . . . Ei, . . . En attached together, on the one hand, by their edges in the axis of revolution AA′ of the ammunition body and, on the other hand, by other edges of the fins, of the wall of said ammunition body and of the skirt, the fins forming, with the skirt and the circular wall, cells for the pyrotechnic charge.
 9. The ammunition as claimed in claim 1, wherein, an ammunition body-central core assembly being produced in a single piece, the ammunition body comprises a cylindrical wall of axis of revolution AA′ merged with the axis XX′ of the ammunition and a central core attached to said cylindrical wall, the cylindrical wall comprising, on the side of the front end of the ammunition body, the circular opening for the booster and, on the side of the rear end of the ammunition body, a rear opening sealed by a skirt, the fins E1, E2, . . . Ei, . . . En of the central core being attached, on one side, by their edges in the axis AA′ of the ammunition body and by other edges, parallel to the axis AA′ of the ammunition body, of the cylindrical wall of the ammunition body, the fins forming, with the skirt and the cylindrical wall, cells for the pyrotechnic charge.
 10. The ammunition as claimed in claim 1, wherein the loading compartment comprises a common loading area followed by a compartmented area, the common loading area being delimited by the booster, the ammunition body wall and by the plane formed by the front end portions of fins of the central core, the compartmented area being delimited by the ammunition body wall and the skirt, the fins E1, E2, . . . Ei, . . . En forming, with the ammunition body wall, cells for the pyrotechnic charge of the ammunition.
 11. The ammunition as claimed in claim 3, wherein the n fins forming the central core are preferentially distributed regularly around the axis of revolution AA′ of the ammunition body to form identical cells intended to contain the pyrotechnic charge.
 12. The ammunition as claimed in claim 1, wherein the central core comprises, in the coupling axis of the edges of the fins, a passage over at least a portion of the length of the central core for the introduction of a pyrotechnic tube igniter.
 13. The ammunition as claimed in claim 12, wherein the wall of the passage, formed by the edges of the n fins E1, E2, . . . Ei, . . . En comprises orifices perpendicular to the axis of the passage enabling the pyrotechnic tube igniter, through these orifices, to laterally ignite, along said axis CC′, the pyrotechnic charge of the ammunition. 